DEFECTIVE NEUTROPHIL ACTIVITY IN FRUCTOSE-1,6-DIPHOSPHATASE DEFICIENCY

Fructose-1,6-diphosphatase is a key enzyme for gluconeogenesis and for inducing substrates initiating the hexose monophosphate shunt. Its de ficiency (McKusick 229700) leads to symptoms occurring from the first days of life including vomiting, hyperventilation, dyspnoea, irritabil ity, somnolence up to coma, moderate hepatomegaly, and muscular hypoto nia; major biochemical features are hypoglycaemia, increased plasma le vels of lactate, 3-hydroxybutyrate and acetoacetate, uric acid, and al anine, ketonuria and increased urinary glycerol excretion (Gitzelmann et al 1989). Defective neutrophil activity (phagocytosis, bactericidal functions and chemotaxis) has not so far been reported as a common fe ature in fructose-1,6-diphosphatase deficiency, while it has been desc ribed in glycogen storage disease type Ib (GSD Ib) (Beaudet et al 1980 ), causing recurrent moderate to severe bacterial and fungal infection s (Ambruso et al 1985). We recently observed two children affected by fructose-1,6-diphosphatase deficiency with defective neutrophil activi ty.